Conductive plastics are used in many different applications where electromagnetic interference and electrostatic discharge must be avoided. Examples include packaging material for consumer electronics, computer or mobile phone housings, piping and tanks for flammable liquids such as gasoline tanks, wires and cables. Conventional plastics (thermoplastics and thermosets) have poor electrical conductivity and are prone to building up static electricity. They can be rendered dissipative or even conductive by adding pulverized conductive material at levels beyond the so called percolation threshold. The resulting compound comprising the plastic and the conductive material is called conductive plastic. The mechanical performance of the plastic, however, suffers from adding pulverized conductive material as impact strength and ductility decrease. High-performing conductive materials attain the percolation threshold at low addition levels, retaining the mechanical performance of the plastic. The most commonly used conductive material is conductive carbon black, a special and expensive grade of carbon black.
Carbon black is produced by pyrolysing oil with fuel gas in a furnace. In the production of conductive carbon blacks, pyrolysis is followed by expensive post treatment steps to increase conductivity, notably steam exposure to increase the surface area and extraction to remove contaminants. Carbon blacks and especially conductive carbon blacks have a strongly negative impact on the environment and a high CO2 footprint due to the fact that fossil raw materials are used in a highly energy intense production process.
There is thus a need for a novel competitive high performing conductive material for the manufacture of conductive plastics.
Additionally, there also exists a need for a conductive material with lower environmental impact and CO2 footprint.
During chemical pulping cellulosic fibers are separated from softwoods, hardwoods, and annual plant biomass, for further processing to paper, board, tissue products or chemicals. Separation is done in a liquid, e.g. the so called white liquor in Kraft pulping or organic solvent as in organosolv processes. Lignin can be isolated from the spent liquor and thereafter be used as a biofuel, or as raw material for chemicals and materials.